via phone Number from Messenger’
The well-known reverse engineer Jane Manchun Wong states that Facebook is extracting the option of locating contacts via a phone number from Messenger, possibly because the option makes it possible to link accounts and random numbers via brute forcing .

Recently another security researcher came out with the news that he was able to link 17 million random telephone numbers to real people via Twitter by entering them in the Twitter app. Among those 17 million people were also prominent politicians. It is possible that Facebook wants to prevent it from appearing in the news for the same reasons.

In the case of Twitter, a randomized set of two billion generated phone numbers was reported to the Android app, which led to the 17 million hits . Twitter says it is working to eliminate this bug, but the question is how the platform will determine whether a specified phone number is random or not. Facebook, by sacrificing the feature, seems to avoid the whole issue.

The ability to track users on a social medium by their telephone number is intended to make the platform easier to use, and of course only works if the targets have entered their number. Also, the person who performs the search must usually also provide his own number.

Wong tweet FB messenger